The disclosure relates to a pilot-controlled pressure limiting valve.
In pressure limiting valves having a main piston which opens up an outlet when a maximum pressure is exceeded, the pressure to be limited acts substantially counter to a regulating spring which acts in the closing direction. With increasing volume flow through the pressure limiting valves, an increase in the seat and/or slide diameter and of the regulating springs is necessary. Here, the necessary spring force increases quadratically with the seat and/or slide diameter.
To keep the installation space within reasonable dimensions, pressure limiting valves are of pilot-controlled design. The main piston of such valves is subjected to an additional pressure loading in the closing direction, wherein said pressure can be dissipated via a pilot control valve. Said pilot control valve is a directly controlled pressure limiting valve. As a result of the additional reducible closing force, the main stage of the valve can be designed to be smaller than that in a directly controlled pressure limiting valve.
The applicant's data sheet RD 64642/11.06 presents, on page 17, an MHDBLS type pilot-controlled pressure limiting valve in which the response behavior of the pilot control stage can be adjusted through the positioning of a control slide. For this purpose, the preload of a pilot control spring which is supported on the control slide is varied. The control slide is loaded on one side by an overdrive spring and on the other side by a control pressure. Here, the overdrive spring acts in a direction for increasing the preload of the pilot control spring, whereas the control pressure acts in a direction for reducing the preload of the pilot control spring.
A disadvantage of such pilot-controlled pressure limiting valves is that the control pressure required for displacing the control slide, and a stop which defines the minimum preload of the pilot control spring, can only be adjusted jointly by rotating an adjusting sleeve in a sleeve.
By contrast, it is the object of the disclosure to provide a pilot-controlled pressure limiting valve in which the flexibility of adjustment possibilities is increased.
Said object is achieved with a pilot-controlled pressure limiting valve.